Thermoregulatory circadian rhythms in the pouched mouse (Saccostomus campestris)

1. Circadian rhythms of body temperature (Tb), oxygen consumption (VO2), and minimal thermal conductance (C) were studied in the pouched mouse, Saccostomus campestris under natural photoperiod during February at a constant ambient temperature of 28 degrees C. 2. Circadian rhythms of body temperature were also studied under natural photoperiod and laboratory temperatures (Max: 28.1 degrees C; Min: 23.2 degrees C) during February. 3. The results of the present study suggest that changes in ambient temperature are not the main "zeitgeber" for body temperature rhythm, and it seems that photoperiod plays a major role in this species. 4. The relationship between the rhythms of Tb, VO2, and C are further discussed.